Laser grade vs. commercial grade optics

Posted by Mike Vergo on

If you are not a regular customer, you likely came to Esco Optics via a google search. When looking at our catalog offerings you may be wondering “will this optical window or lens work in my laser experiment?” The answer could be yes, but it could also be no. The truth lies in what are you trying do and what is the power of your laser?  

 Laser experiment, laser grade optical window, optical laser window

The difference between laser-grade and commercial-grade optics primarily lies within precision level of both polishing and finishing processes. I have had customers love the price of commercial optics, but their application really warrants laser grade, which of course, will cost more due to higher quality of the finished part. In optics, precision is everything and clear specifications exists that separates the two.  For example, when you are talking about mirrors, the specifications matter across the whole surface for reflectivity. When considering transmissive optics, the center beam surface is the most important specification and less so across the whole part. The table below compares key specifications for laser grade windows.  

Key Differences Between Laser-Grade and Commercial-Grade Optics 

 

Laser-Grade Optics 

Commercial-Grade Optics 

Surface Roughness 

1nm RMS 

< 3nm RMS 

Scratch/Dig Specs 

10/5 - 20/10 

40/20- 60/40 

Wavefront accuracy 

λ/4 or better 

1λ or λ/2 

Coating 

High-damage-threshold coatings for lasers 

Standard anti-reflection or protective coatings 

Applications 

High-power lasers, scientific research, military/defense 

Consumer electronics, general imaging, lighting 

 

Laser-Grade Optics
Laser-grade optics are used in highly demanding environments where precision and performance are critical. These components are typically found in applications such as scientific research, medical devices, military equipment, and high-powered laser systems. 

  • Surface Quality: Polishing for laser-grade optics is extremely precise, often achieving surface roughness below 1 nm (nanometer). The goal is to create a nearly perfect optical surface to prevent any beam scattering which could reduce efficiency or cause unwanted distortions in laser systems. 
  • Scratch/Dig Specifications: Laser-grade optics often have surface quality specified as 10/5 or 20/10 (scratch/dig) which indicates extremely low tolerances for imperfections. 
  • Minimal subsurface damage: SSD is achieved by using properly controlled material removal processes from rough grind followed by a longer fine grind that prevents microcracks or defects in the near-surface layer of the optical material. The final polishing process leaves the material surface as pristine as possible.    
  • Wavefront Distortion: The optics must exhibit minimal wavefront distortion as even small aberrations can significantly impact the performance of a laser system. Typical laser-grade optics aim for λ/4 or better wavefront accuracy. 

Examples of laser-grade applications: 

  • High-power laser cutting systems 
  • Optical assemblies in scientific instruments 
  • Laser communication systems 
Precision optics metrology, optics inspection, scratch/dig inspection

 

Commercial-Grade Optics
Commercial-grade optics are used in less demanding applications where the highest level of precision is not as critical. These components are often found in devices like consumer cameras, lighting systems, optical sensors, and general-purpose lenses. 

  • Surface Quality: Polishing for commercial-grade optics is less stringent, typically achieving surface roughness in the range of 10–50 nm. This is sufficient for most non-laser optical applications where minor imperfections are tolerable. 
  • Scratch/Dig Specifications: Commercial-grade optics usually have surface quality specifications of 40/20 or 60/40 which allow for a greater number of minor surface imperfections. 
  • Wavefront Distortion: These optics do not require the same level of wavefront control as laser-grade optics. Tolerances are generally in the range of 1λ or λ/2 which is suitable for imaging or light-gathering applications but would be inadequate for precision laser work. 
  • Coatings: The finishing process may involve simpler coatings, such as basic anti-reflection coatings, that don't need to withstand extreme laser power. 

Examples of commercial-grade applications: 

  • Cameras and binoculars 
  • Lighting systems 
  • Optical instruments for non-critical applications 
  • Sensing and environmental monitoring technology 

Conclusion
The level of polishing and finishing determines the final quality and performance of an optic. For laser-grade optics, where precision and performance are paramount, both polishing and finishing involve extremely tight tolerances in material removal, resulting in smooth surfaces, minimal defects, and high-quality coating performance. In contrast, commercial-grade optics can tolerate more imperfections and have lower standards for surface quality and wavefront distortion making them suitable for everyday applications where ultra-high precision is not necessary. Understanding these distinctions helps in selecting the right optics for your needs, whether it is for a cutting-edge laser system, or a consumer-grade optical device. Please reach out to us at Sales@EscoOptics.com for all your optical needs. 

 

Read more from my blog series 

Optical Design for Manufacturability
Optical Coatings and Cost

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